<!DOCTYPE html>
<html lang="en">
<body>
	<select size="4" multiple="multiple">
		<option value="option1">option one</option>
		<option value="option2">option two</option>
		<option value="option3">option three</option>
		<option value="option4">option four</option>
	</select>
	<script
		src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
	<script>
		(function($) {
			// Set the value of the selected options 
			$('select').val([ 'option2', 'option4' ]);
			// Get the selected values 
			alert($('select').val().join(', ')); // Alerts, "option2, option4"  
		})(jQuery);
	</script>
</body>
</html>